8 Tips and Tricks for Improving Rolling Stock Lighting ( Robert J. Wilkins Oct 2017)

The following are some ideas and suggestions for improving the lighting in your HO

rolling stock including passenger cars and cabooses.

1) Enhance Illumination: Use a strip of heavy duty aluminum wrap and glue to the ceiling of the cab to provide a

reflective surface that will shed more light into the cabin. The interior of the cabin should

be painted black to prevent the lighter color of the plastic from showing through .

The cabin interior has been darkened with a black paint coat. Heavy Duty Aluminum is cut to the outline of the ceiling.

Use adhesive putty (Tip 6) to stick the aluminum strip. Press onto the ceiling with the reflective side showing.

2) Install a slide or press-on/off switch to deactivate lights. With DCC constant track voltage around 12-15 Volts lights in passenger cars and

cabooses will stay on even when the car is in a siding. This will also occur in DC mode if

the siding is powered. A simple solution is to add a slide switch to the undercarriage of

the rolling stock by cutting one of the pickup leads. The photos below describe a process

for adding a SPDT slide switch.

A hole is cut in the floor of the car. I used a drill and Dremel cutting disc to cut out this rectangular hole.

The switch is inserted and glued with CA (Super) Glue into place.

One of the pickup leads is cut and soldered to the center and one pole of the switch.

3) Add Windows Some rolling stock comes without window panes included. These empty windows can be

readily filled in using clear plastic material such as clear plastic protector sheets or from

clear plastic packing material. Cut out a patch to a size larger than the window and glue

in on the edges with liquid plastic glue. You can also use 2 pieces of clear adhesive tape

stuck onto one another. One piece just larger than the window and the second larger than

the first to provide adhesive at the edges for sticking to the wall around the window.

Small panels of clear plastic are glued to the perimeter of the windows.

Finished Window treatment.

4) How Many LEDs to use and what arrangement should be used ? The LED Driver chip generates a constant 20 milliamps of current starting at 5 volts for

the first LED. The chip is rated for a maximum voltage of 90 volts regulating the current

output to 20 milliamps so the LEDs will not burn out. No resistors are required.

The resistance of an LED has been calculated to be small around 13 ohms hence this is

not a factor in changing voltage. What is important is the voltage drop generated by each

LED, termed its forward Voltage, when added to a circuit. LEDs vary in their in their

forward voltage drop. Yellow, Orange and Red LEDs have a forward voltage drop of

around 2 volts while White, Blue and Green have a forward voltage drop of around 3.3

volts. When LEDs are arranged in series (ie Pos-Neg-Pos-Neg etc) for every LED added

the required voltage to illuminate the circuit will rise by the forward voltage of the LED.

For DCC operation, operating at between 12-15 volts this would allow 3 to 4 LEDs to be

used when arranged in a series circuit. (depending on forward voltage LEDs)

If using DC the threshold voltage for the LEDS to illuminate an in series setup would be

too high (over 10 volts).If however the LEDS are arranged in parallel (ie Neg- Pos-Pos-

Neg ) the voltage drop proves to be much lower. Three LEDs with the same forward

voltage drop, set up in parallel, will require a threshold voltage around 1 volt higher than

the initial voltage of 5 Volts required by the LED Driver chip. A total of 6.0 volts.

To illustrate the 3 red LEDs (above) are set up in parallel. Using a regulated voltage the 3 red LEDS light up initially around 5.5 volts with good illumination around 6.0 Volts. The current reading is shown in the lower meter reading at 0.01 amps. (ie between 10 and 20 milliamps. ) Most LEDs begin to light at around 10 milliamps.

If a LED of higher voltage drop is added into the parallel circuit it will not illuminate yet

the others will. This is shown below. Why this occurs I am not sure. If someone has an

explanation please let me know. It may be related to the difference in voltage drop.

2 Red LEDs + 1 White LED Set up in parallel. White does not

light.

2 Red LEDs set in parallel + 1 White LED set in series. All LEDs Light

This requires a higher threshold voltage (7.4V) and 20 mamps of current

If this LED is added in series to the 2 parallel arranged LEDs it will light quite brightly

at around 7 Volts. The voltage drop of the white LED explains a higher threshold voltage

is required to light the circuit.

Bottom line : The best circuit for DC use no more than 3 LEDs. If all are of the same

type or have the same forward voltage they should be setup in parallel. If one of the

LEDs has a higher Forward voltage use a parallel arrangement for the 2 LEDs (eg 2 red

LEDs) and put the other LED (White or Yellow) in series setup to the red LEDs. Under

these circumstances the lights should illuminate adequately at around 7 volts.

Here is the circuit set up for the Caboose lighting system using either the Yellow or Soft

white LED. The VB lead of the LED Driver unit connects to the Positive leads of the Red

LEDs and the Negative lead from the White or Yellow LED connects to the Bridge

Rectifier/Capacitor Negative Junction. This circuit works fine with DCC as well.

Note : The Yellow LED will still work when connected in Parallel to the red LEDs as it

has the same forward voltage drop.

Setup for Caboose Lighting when using the Soft White LED

5) Use the new 2mm Red LEDs. 2mm LEDs are now available and the smaller size

makes them more prototypical for HO scale rear lights.

These 2 mm LEDs will now come standard with the

Caboose lighting kit replacing the 3mm size.

Because of the wider body shape they may require

manipulation into place in the cabin. The forward voltage

of these LEDs is around 2V.

6) Use Blu Tack Putty for temporary adhesion.

This putty like material is available under a number of names including (Blu Tack

Brand- Adhesive Putty, Scotch Brand- Removable Mounting Putty, Loctite Brand -

Fun Tack, Duck Brand Poster Putty). This is used as a versatile, malleable, reusable,

temporary sticky adhesive. It is inexpensive and readily available in beige or blue from

Stationary Stores, Home Stores, Arts and Craft Stores and Online.

In this project it is used to attach weight plates to the rolling stock floor or install light

circuit components and carriage interior seating and passengers.

Blu Tack Putty is used here to secure metal weight to the floor of this caboose.

Blu Tak Putty used here to secure the light circuit, the LED Driver Unit the carriage interior seating, passengers and weights .

7) The best location for the pickup wire hole. I have found that the best location for drilling the hole in the

floor of the undercarriage is as close to the central pivot point

of the truck but clear of the copper pickup collar.

This allows for minimal lateral movement of the copper collar

on the axle and tension on the wire and solder joint. Note here the pickup hole for the pickup wire has been drilled in the middle of the floor between the copper collar/axle and the central pivot point of the truck. This allows the truck to turn freely with minimal pulling on the collar. Make sure there is enough slack to allow gravity on the copper collar to make contact with the electrified axle. Also be sure that the insulated part of the wire is not rubbing against the collar preventing wheel rotation.

What if the truck cannot hold the second collar ? :

In this case simply use the other truck for the second collar. Here the coupling mechanism prevents the wiring of a collar to the front wheel of the truck. The collar is now placed on the other truck wheel to overcome this problem.

8) Add or Modify the Coupler You may wish to change the couplers of the Rolling stock from hook type to knuckle

type couplers. You could also modify the hook type coupler to be compatible with the

knuckle type. I have included a description on how this can be accomplished below.

A You Tube video was produced by TrainTrackTrav that describes this process. "How to Make Clever Adaptor Coupler" :https://www.youtube.com/watch?v=l3mW8MPSi3Y

1. Snip off the wing of the hook coupler

2. Optional: Snip off the downward pointing uncoupler or at least the pointed projection.

3. File down the hook to be compatible with the knuckle hook.

4. Once the trimming of the hook is compatible with the knuckle coupler hook, reattach the couplers to the car.